Enable paragraph linking in EPUB

src/imxml2epub.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8; mode: python -*-
-# Time-stamp: <2020-09-25 08:08:41 (kthoden)>
+# Time-stamp: <2020-09-25 14:10:21 (kthoden)>
 
 """ Convert a customized DocBook XML file into a set of files that
 constitute the contents of an EPUB file.
@@ -292,6 +292,7 @@ def addToContentopf(contentopf, Filename, FileID, Mediatype):
             "xml" : "application/xhtml+xml",
             "jpg" : "image/jpeg",
             "png" : "image/png",
+            "svg" : "image/svg+xml",
             "bitstream" : "application/octet-stream"
         }
         contentopfns = "{http://www.idpf.org/2007/opf}"
@@ -1835,6 +1836,54 @@ class FootnoteError(Exception):
         if xmlPublicationreference.get("rel") == "popover":
             xmlPublicationreference.tag = "EOAcitation"
 
+
+logging.info(f"{logseparator}Creating paragraph links")
+libeoaconvert.debug_xml_here(
+        xmlEbookTree,
+        "epubtree_beforeparagraphlinks",
+        DEBUG_DIR
+)
+
+# for correct linking, get all parts and chapters
+xml_parts_and_chapters = xmlEbookTree.xpath("//div0|//div1")
+paragraphs_with_corresp = xmlEbookTree.xpath("//p[@corresp]")
+if len(paragraphs_with_corresp) > 0:
+    shutil.copy(
+        EPUB_FILES / "icon-translation.svg",
+        OUTPUT_DIR / "OEBPS/images/icon-translation.svg"
+        )
+
+    contentopf = addToContentopf(
+        contentopf,
+        "images/icon-translation.svg",
+        "icontranslation",
+        "svg"
+    )
+
+for pc in paragraphs_with_corresp:
+    corresponding_attribute = pc.get("corresp")[1:]
+    corresponding_paragraph = xmlEbookTree.xpath(f"//p[@xml:id='{corresponding_attribute}']")
+    if len(corresponding_paragraph) == 0:
+        logging.error("There seems to be no corresponding xml:id for %s. Exiting." % corresponding_attribute)
+        sys.exit(1)
+    elif len(corresponding_paragraph) > 1:
+        logging.error("The xml:id %s has been assigned more than once. This is not allowed. Exiting." % corresponding_paragraph[0].attrib["{http://www.w3.org/XML/1998/namespace}id"])
+        sys.exit(1)
+    else:
+        eoa_id_element = corresponding_paragraph[0]
+        for xml_parent in eoa_id_element.iterancestors():
+            if xml_parent.tag == "div1":
+                chapter_element = xml_parent
+        chapter_element_index = xml_parts_and_chapters.index(chapter_element) + 1
+        paratext_link = etree.Element("a")
+        paratext_link.set("id", pc.attrib["{http://www.w3.org/XML/1998/namespace}id"])
+        href_text = f"chapter{chapter_element_index}.xhtml#{eoa_id_element.attrib['{http://www.w3.org/XML/1998/namespace}id']}"
+        paratext_link.set("href", href_text)
+        paratext_link.set("class", "paralleltext")
+        paratext_icon = etree.SubElement(paratext_link, "img", src="images/icon-translation.svg", alt="link to parallel text", height="14px")
+        paratext_link.tail = " "
+        pc.insert(0, paratext_link)
+
 ##############################################################
 #              Finish ePub Conversion, save File             #
 ##############################################################
@@ -1846,7 +1895,7 @@ class FootnoteError(Exception):
     xmlIndexentry.clear()
     xmlIndexentry.tail = tmpTail
 etree.strip_tags(xmlEbookTree, "EOAlabel", "EOAindex", "EOApageref", "EOAcitenumeric", "EOAtable", "EOAref",  "note", "div", "div2", "div3", "div4", "div5", "citetext", "newpage", "EOAciteyear", "EOAtablelabel" , "hi", "pagebreak", "page", "pagestyle", "EOAcitation", "EOAciteauthoryear", "EOAcitemanual", "EOAprintbibliography", "EOAindexperson", "EOAprintindex", "EOAindexlocation", "EOAprintpersonindex", "EOAprintlocationindex","anchor", "temp", "EOAletterhead", "EOAhifigure", "EOAtocentry","tagtobestripped")
-etree.strip_attributes(xmlEbookTree, "id-text", "noindent", "type", "label", "spacebefore", "rend", "hielement") # also contained "id"
+etree.strip_attributes(xmlEbookTree, "id-text", "noindent", "type", "label", "spacebefore", "rend", "hielement", "corresp") # also contained "id"
 etree.strip_elements(xmlEbookTree, "citekey", "originalcontents", "elementtoberemoved", with_tail=False)
 
 logging.info("Write every Part and Chapter into one file")